Waldo is a city in Columbia County, Arkansas, United States. The population was 1,594 at the 2000 census. Waldo celebrated its 120th year as a city in 2007. The small town was once a booming rail city on the Cotton Belt train route. The city has a rail museum with various displays showing its rail history. The city began to wane in population in the 1950s when neighboring Magnolia began drawing industry. Waldo was also home of the Waldo High School Bulldogs basketball teams. Consistently these teams made playoffs and on numerous occasions won the state championship. The legacy of Waldo School will carry on in the community despite its closing in 2005.
Waldo is located at 33°21′07″N 93°17′40″W / 33.351944°N 93.294372°W / 33.351944; -93.294372.
According to the United States Census Bureau, the city has a total area of 2.2 square miles (5.7 km²), all land.